Electrolytic processing apparatus and method

Abstract

An electrolytic processing apparatus can planarize uniformly over an entire surface of a substrate under a low pressure without any damages to the substrate. The electrolytic processing apparatus has a substrate holder configured to hold and rotate a substrate having a metal film formed on a surface of the substrate and an electrolytic processing unit configured to perform an electrolytic process on the substrate held by the substrate holder. The electrolytic processing unit has a rotatable processing electrode, a polishing pad attached to the rotatable processing electrode, and a pressing mechanism configured to press the polishing pad against the substrate. The electrolytic processing unit also has a liquid supply mechanism configured to supply an electrolytic processing liquid between the substrate and the rotatable processing electrode, a relative movement mechanism operable to move the substrate and the rotatable processing electrode relative to each other, and a power supply configured to applying a voltage between the rotatable processing electrode and the metal film of the substrate so that the rotatable processing electrode serves as a cathode and the metal film of the substrate serves as an anode.

1 . An electrolytic processing apparatus comprising: 
 a substrate holder configured to hold and rotate a substrate having a metal film formed on a surface of the substrate; and    an electrolytic processing unit configured to perform an electrolytic process on the substrate held by said substrate holder, said electrolytic processing unit comprising: 
 a rotatable processing electrode;  
 a polishing pad attached to said rotatable processing electrode;  
 a pressing mechanism configured to press said polishing pad against the substrate;  
 a liquid supply mechanism configured to supply an electrolytic processing liquid between the substrate and said rotatable processing electrode;  
 a relative movement mechanism operable to move the substrate and said rotatable processing electrode relative to each other; and  
 a power supply configured to applying a voltage between said rotatable processing electrode and the metal film of the substrate so that said rotatable processing electrode serves as a cathode and the metal film of the substrate serves as an anode.  
   
     
     
         2 . The electrolytic processing apparatus as recited in  claim 1 , wherein said rotatable processing electrode has a diameter smaller than a diameter of the substrate.  
     
     
         3 . The electrolytic processing apparatus as recited in  claim 1 , wherein said liquid supply mechanism comprises at least one through-hole formed in said rotatable processing electrode and said polishing pad for allowing the electrolytic processing liquid to pass therethrough.  
     
     
         4 . The electrolytic processing apparatus as recited in  claim 3 , wherein said electrolytic processing unit further comprises a hollow shaft having an upper end to which said rotatable processing electrode is attached, 
 wherein said liquid supply mechanism further comprises a liquid supply passage formed in a hollow portion of said hollow shaft for supplying the electrolytic processing liquid to said at least one through-hole.    
     
     
         5 . The electrolytic processing apparatus as recited in  claim 1 , wherein said electrolytic processing unit further comprises a hollow shaft having an upper end to which said rotatable processing electrode is attached, 
 wherein said pressing mechanism comprises a pneumatic pressure actuator operable to press said hollow shaft in an axial direction.    
     
     
         6 . The electrolytic processing apparatus as recited in  claim 1 , wherein said polishing pad comprises a fixed abrasive pad.  
     
     
         7 . The electrolytic processing apparatus as recited in  claim 1 , wherein said polishing pad comprises a resin pad having projections formed continuously on a surface of said resin pad.  
     
     
         8 . The electrolytic processing apparatus as recited in  claim 1 , further comprising: 
 a loading/unloading section configured to load and unload the substrate; and    a carrier configured to move the substrate between said loading/unloading section and said electrolytic processing unit.    
     
     
         9 . The electrolytic processing apparatus as recited in  claim 8 , wherein said carrier comprises: 
 a support block configured to support said substrate holder;    a horizontal movement mechanism operable to move said support block in a horizontal direction; and    a vertical movement mechanism operable to move said substrate holder in a vertical direction.    
     
     
         10 . The electrolytic processing apparatus as recited in  claim 8 , further comprising a cleaning unit configured to clean the substrate.  
     
     
         11 . The electrolytic processing apparatus as recited in  claim 10 , wherein said cleaning unit comprises a nozzle configured to eject at least one of a cleaning liquid and a clean gas toward the substrate.  
     
     
         12 . The electrolytic processing apparatus as recited in  claim 1 , wherein said substrate holder comprises: 
 a housing;    a feed terminal provided on said housing, said feed terminal being brought into contact with a peripheral portion of the substrate;    a seal disposed at a radially inward position of said feed terminal;    a plate operable to press the substrate placed on said feed terminal and said seal against said housing; and    an electric wire connecting said feed terminal to said power supply.    
     
     
         13 . The electrolytic processing apparatus as recited in  claim 1 , wherein said substrate holder comprises a plate operable to attract the substrate to a surface of said plate, 
 wherein said electrolytic processing unit comprises: 
 a feed contact which can feed an electric current to a peripheral portion of the substrate attracted to said plate; and  
 an electric wire connecting said feed contact to said power supply.  
   
     
     
         14 . The electrolytic processing apparatus as recited in  claim 13 , wherein said feed contact comprises: 
 a conductive ball which can be brought into contact with the peripheral portion of the substrate;    a rod configured to support said conductive ball;    a spring configured to bias said rod;    a case housing said conductive ball so that a portion of said conductive ball is exposed from a top of said case; and    a holder holding said conductive ball, said rod, and said spring.    
     
     
         15 . The electrolytic processing apparatus as recited in  claim 14 , wherein each of said rod and said holder has a passage for supplying an electrolyte to said conductive ball.  
     
     
         16 . The electrolytic processing apparatus as recited in  claim 15 , wherein the electrolyte is the same kind of liquid as the electrolytic processing liquid.  
     
     
         17 . The electrolytic processing apparatus as recited in  claim 14 , wherein said conductive ball is made of graphite.  
     
     
         18 . The electrolytic processing apparatus as recited in  claim 13 , wherein said feed contact comprises: 
 a roller having a conductive surface which can be brought into contact with the peripheral portion of the substrate, said roller being rotatable about a shaft perpendicular to a rotation axis of the substrate;    a holder configured to support said roller; and    a feed terminal which can be brought into contact with said conductive surface of said roller, said feed terminal being housed in said holder.    
     
     
         19 . The electrolytic processing apparatus as recited in  claim 18 , wherein said feed contact further comprises a synchronization mechanism operable to synchronize rotation of said roller and rotation of the substrate.  
     
     
         20 . The electrolytic processing apparatus as recited in  claim 13 , wherein said feed contact comprises: 
 a roller having a conductive surface which can be brought into contact with the peripheral portion of the substrate, said roller being rotatable about a shaft perpendicular to a rotation axis of the substrate;    a holder configured to support said roller and hold an electrolyte therein; and    a feed terminal configured to feed an electric current to said conductive surface of said roller via the electrolyte held in said holder.    
     
     
         21 . The electrolytic processing apparatus as recited in  claim 13 , wherein said feed contact comprises: 
 a roller having a conductive surface which can be brought into contact with a bevel portion of the substrate, said roller being rotatable about a shaft parallel to a rotation axis of the substrate; and    a retainer operable to press said roller against the bevel portion of the substrate.    
     
     
         22 . The electrolytic processing apparatus as recited in  claim 13 , wherein said feed contact comprises: 
 a feed terminal connected to said power supply;    a holder configured to hold an electrolyte between the metal film of the substrate and said feed terminal; and    a liquid supply pipe configured to supply the electrolyte to said holder.    
     
     
         23 . The electrolytic processing apparatus as recited in  claim 22 , wherein said feed terminal further comprises a resilient pad which can be brought into contact with the substrate.  
     
     
         24 . An electrolytic processing method comprising: 
 rotating a substrate having a metal film formed on a surface of the substrate;    rotating a polishing pad attached to a processing electrode;    supplying an electrolytic processing liquid between the substrate and the processing electrode;    applying a voltage between the processing electrode and the metal film of the substrate so that the processing electrode serves as a cathode and the metal film of the substrate serves as an anode;    pressing the polishing pad against the substrate; and    moving the processing electrode relative to the substrate in a radial direction of the substrate.    
     
     
         25 . The electrolytic processing method as recited in  claim 24 , wherein said moving comprises moving the processing electrode relative to the substrate by at least a sum of a diameter of the substrate and a diameter of the processing electrode.  
     
     
         26 . The electrolytic processing method as recited in  claim 24 , wherein said moving comprises moving the processing electrode while fixing the substrate.  
     
     
         27 . The electrolytic processing method as recited in  claim 24 , wherein said moving comprises moving the processing electrode and the substrate relative to each other at relative movement speeds which are set for each of areas in the substrate, said areas being divided in a radial direction of the substrate.  
     
     
         28 . The electrolytic processing method as recited in  claim 27 , wherein the relative movement speeds are set at each area of the substrate so that each area of the substrate has substantially the same total period of time during which the processing electrode faces the area of the substrate.  
     
     
         29 . The electrolytic processing method as recited in  claim 27 , wherein said moving comprises starting relative movement at an area for which the smallest relative movement speed is set.  
     
     
         30 . The electrolytic processing method as recited in  claim 27 , wherein said moving comprises finishing relative movement at an area for which the smallest relative movement speed is set.  
     
     
         31 . The electrolytic processing method as recited in  claim 24 , further comprising applying a voltage between the processing electrode and the metal film of the substrate so that the processing electrode serves as an anode and the metal film of the substrate serves as a cathode to electrolytically etch a metal produced on a surface of the processing electrode.